In a long jump competition there are 15 participants  $P_1,P_2,\mathrm{.......},P_{15}$ from different schools. They have to perform their jumps in a random order given by the event referee. In the given order if  $P_1$ has to jump before  $P_5,$ then the probability that  $P_2$ has to jump immediately after  $P_1$ is equal to  $\frac{1}{K},(K\in N)$ then sum of the digits of  $\text{'}K\text{'}$ equals